CD-113 SHIELDING TENSORS OF MONOMERIC CADMIUM COMPOUNDS CONTAINING NITROGEN DONOR ATOMS .1. CP/MAS STUDIES ON CADMIUM POLY(PYRAZOLYL)BORATE COMPLEXES HAVING N-4 AND N-6 COORDINATION ENVIRONMENTS

The principal elements of the Cd-113 shielding tenser for a series of complexes containing nitrogen donor atoms were determined via cross polarization/magic angle spinning (CP/MAS) nuclear magnetic resonance experiments. The N-4 coordination compound [H2B(pz)(2)Cd has an isotropic chemical shift of 291.9 ppm (all Cd-113 chemical shifts are referenced to an external sample of 0.1 M Cd(ClO4)(2) in 1:1 H2O) in the solid state. The chemical shift anisotropy and asymmetry parameter of [H2B(pz)(2)]Cd-2 are 280.0 ppm and 0.04 for Delta sigma and eta, respectively. The three N-6 coordination compounds [HB(3,5-Me(2)pz)(3)]Cd-2, [B(pz)(4)]Cd-2, and [B(3-Mepz)(4)]Cd-2 have the isotropic chemical shifts of 175.4, 217.7, and 187.9 ppm, respectively, in the solid state. The chemical shift anisotropies and asymmetry parameters for these N-6 complexes are -210.2, -277.3, and -263.4 ppm and 0.07, 0.65, and 0.23, respectively. Using available X-ray crystallography data and previous shielding/symmetry relations, the Cd-113 shielding tensors are described with respect to the molecular axis system.